Phenotypic Plasticity – Alternate Transcriptional Programs Driving Treatment Resistant Prostate Cancer

Androgen deprivation therapy (ADT) that antagonizes androgen receptor (AR) signaling has made significant increases to overall survival of prostate cancer patients. However, ADT is not curative, and patients eventually progress to castration resistant disease (CRPC). It has become evident that a subset of prostate cancers acquire ADT resistance through mechanisms independent of AR alteration or reprogramming of AR signaling. This approximately involves a quarter of prostate cancers progressing on ADT. Collectively, these tumors evolve via phenotypic plasticity and display the activation of developmental and stemness gene signatures as well as transitional programs including an epithelial-mesenchymal phenotype. Currently, no successful treatments exist for prostate cancer patients to inhibit or reverse prostate tumor progression that utilizes mechanisms of epi-plasticity. This overview will discuss epigenetic mechanisms that mediate phenotypic plasticity and the potential for targeting the epigenome to create a novel direction for combination strategies involving epigenetic therapy to provide durable response.